1. Field of the Invention
This invention relates to spray nozzles and, more particularly, to spray nozzles for aerial spraying having adjustable rates of delivery for the sprayed liquid.
2. Description of the Prior Art
U.S. Pat. No. 4,221,334, dated Sept. 9, 1980, the inventor of which is the inventor of the apparatus of the present invention, discloses a nozzle for aerial spraying which includes a plurality of orifices, each of a different size, for delivering selectively different quantities of liquid to be sprayed from the nozzle. The apparatus also includes a circular concave face adjacent to the discharge nozzle against which the liquid flows from the discharge nozzle for providing a fan-shaped spray of the fluid. In the apparatus of the '334 patent the quantity or flow of the liquid to be sprayed may be selectively varied by aligning a particular sized hole or orifice with a fluid supply port, but the particular droplet size of the fluid is predetermined by the curvature of the face that the fluid impinges upon. Thus, while the quantity of the fluid sprayed may be varied, the spray is of a particular particle size and a particular fan-shaped configuration regardless of the particular delivery orifice selected.
Prior to the '334 patent, spray apparatus for aerial delivering generally included a fixed nozzle assembly. If a different flow rate were desired from the flow rate provided by the nozzles on a particular airplane, each nozzle had to be changed to a different nozzle which provided a different flow rate.
With the apparatus of the '334 patent, the same nozzle could be utilized by merely changing the orifice size aligned with the fluid delivery port. The prior art nozzles, again prior to the '334 apparatus, provided a generally cone-shaped swirl of the fluid as it left the spray nozzles or heads. The conical spray took a period of time, which was measured in terms of height before a uniform spray, or a continuous sheet of spray, was formed by the separate conical spray configurations. The apparatus of the '334 patent provides that the spray is initially distributed in a fan shape. Accordingly, the fluid sprayed from the spray heads combines with the spray from the adjacent spray heads to form a relatively uniform curtain very quickly after departure from the spray nozzles. The provision of the fan-shaped spray emanating from each nozzle thus provides a relatively uniform sheet of spray from the aircraft regardless of the height of the aircraft above the delivery target, which is usually an agricultural crop, etc.
The aerial spray apparatus of the prior art does not suggest the provision of changing the droplet size of the spray. By varying the droplet size, a particular spray can be designed or determined in accordance with the desired application of the fluid being sprayed. In other words, the droplet size and delivery quantity may, with provisions for an adjustable nozzle and an adjustable particle size, be coordinated or correlated with respect to the intended target of the spray activity. Thus it may be desirable to have different droplet sizes for spraying a cotton crop than, for example, when spraying trees. The provision of both a variable delivery rate and a variable droplet or particle size accordingly appears to be highly desirable.